Geometry 3.6 – 3.7 Brett Solberg AHS ‘11-’12

Warm-up x y Find the slope of the following. 𝑚= 𝑦 2 − 𝑦 1 𝑥 2 − 𝑥 1 1) (0, 2) (2, 4) 2) (-2, 5), (4, -7) 3) Find the measure of x and y. 4) A regular polygon has an interior angle of 144˚. How many sides does the polygon have? Do you have questions from your HW? x y

Upcoming Events Today Oct 17 3.6 Wed Oct 19 3.7 Tue Oct 25 Review Thu Oct 27 Test

Today’s Agenda Writing Equations Graphing Lines Slope-Intercept Form Standard Form Point-Slope Form Graphing Lines Vertical and Horizontal Lines graph write

Slope-Intercept Form y = mx + b Graphing y = 2x - 3 m = slope b = y-intercept Graphing Plot y-intercept Use slope for 2nd point Connect the dots y = 2x - 3

Standard Form Ax + By = C Graphing 2x + 4y = 12 A, B, and C are numbers Graphing Set x = 0 to find the y intercept Set y = 0 to find the x-intercept Connect the Dots 2x + 4y = 12 If x = 0, then y = 3 If y = 0, then x = 6

Transforming How do you switch from Standard Form to Point-Slope Form? 2x + 4y = 8 y = -½x + 2 Solve for y. 4y = -2x + 8 y = -½x + 2

Point-Slope Form 𝒚− 𝒚 𝟏 = 𝒎(𝒙− 𝒙 𝟏 ) 𝒚− 𝒚 𝟏 = 𝒎(𝒙− 𝒙 𝟏 ) ( 𝑥 1 , 𝑦 1 ) is a point on the line m = slope Graphing Plot point given in line Use slope to plot 2nd point Connect the dots y – 2 = -¾(x – 4) (4, 2)

Writing Equations Pick the equation that is easiest m = 2 (2, -4) Point-Slope Form y +4 = 2(x – 2) m = -1 y-int = 8 Slope-Intercept Form y = -x + 8 (2, 3) (-3, -4) 𝑚= −4−3 −3−2 = 7 5 (y – 3) = 7 5 (x – 2)

Horizontal Lines Lines where y is the only variable are horizontal lines. y = mx + b The slope is zero y = b Graph y =2 Graph y = -1

Vertical Lines Lines where x is the only variable are vertical lines. These lines have an undefined slope. slope = 𝑟𝑖𝑠𝑒 𝑟𝑢𝑛 run = o Graph x = -2 Graph x = 1

Homework 3-6 Worksheet Pg. 169 # 1-37 odd graph paper on side table